共查询到20条相似文献,搜索用时 382 毫秒
1.
2.
光致变色分子经掺杂或键合作用嵌在液晶聚合物中可形成光致变色液晶聚合物,在线性偏振光或非偏振光的照射下,此物质中光致变色分子的构型变化会引起整个液晶分子的二维或三维光致再取向的形成,本文综述了光致变色液晶聚合物的光致再取向的近期研究进展. 相似文献
3.
基于定向电纺纤维膜的可调制偏振片的制备 总被引:2,自引:1,他引:1
基于定向静电纺丝技术制备了高取向性有序纤维薄膜, 利用有序纤维对液晶分子取向的诱导, 构建了可调制散射型偏振片. 填充混合液晶的有序聚甲基丙烯酸甲酯纤维薄膜在可见光范围内, 表现出明显的偏光特性. 混合液晶中光敏性偶氮液晶4-正丁基-4'-甲氧基偶氮苯在360 nm紫外光照射下进行顺反异构转变, 诱导混合液晶发生从各向异性到各向同性的相变. 利用混合液晶光致相变与有序纤维的耦合, 实现了薄膜偏光特性的光控切换. 相似文献
4.
交联液晶高分子兼具液晶的各向异性和高分子网络的弹性,并且具有优异的分子协同作用.在交联液晶高分子中引入光响应基团,例如偶氮苯后,即可赋予其光致形变性能,利用分子协同作用可以将光化学反应引起的分子结构变化放大为宏观形变,从而将光能直接转化成机械能.通过合理的分子结构和取向设计可以使液晶高分子产生诸如伸缩、弯曲、扭曲、振动等多种形式的光致形变,并用于各类光控柔性执行器件的构筑,在人工肌肉、微型机器人、微量液体操控等领域呈现出独特的优势和广阔的应用前景.本文总结和评述了光致形变液晶高分子的研究,包括材料结构对光致形变性能的影响、新型可加工光致形变材料的研究、利用可见光和近红外光触发形变的策略,以及光致形变液晶高分子微执行器在微量液体操控中的应用,最后展望了该领域的发展方向. 相似文献
5.
通过表面摩擦、施加外电场(或磁场)和应力剪切等手段使液晶单体取向后进行光聚合反应是制备高度取向、高度均匀和高度透明高分子液晶膜的重要方法。它在高分子非线性光学材料、导电商分子材料和光纤涂层等领域中具有广泛的应用前景。 相似文献
6.
7.
液晶取向膜是液晶显示器中的关键材料,为了制得性能优良的液晶取向膜,我们通过铃木偶联反应制备了3种含有不同末端基团的3,5-二氨基联苯,将制得的3种二胺单体分别与环丁烷四甲酸二酐聚合得到3种新型的聚酰亚胺。 利用核磁氢谱对单体和聚合物的结构进行了表征,测试了聚合物的溶解性、热稳定性以及用作液晶取向膜的性能。 结果表明,所得的聚酰亚胺具有良好的溶解性和热稳定性,经过机械摩擦后,末端带有甲氧基的聚酰亚胺能使液晶分子平行于摩擦方向取向,末端带有苯氧羰基和联苯氧羰基的聚酰亚胺能使液晶分子垂直于摩擦方向取向。 此类可溶性的聚酰亚胺液晶取向膜将简化制备工艺并在柔性显示器件中具有较大的应用价值。 相似文献
8.
以含肉桂酸基团的光敏聚酰亚胺为"墨水",通过软印刷技术制备了一种新型的可进一步光交联的表面起伏光栅,研究了各向异性光交联对光栅热稳定性和光栅诱导液晶取向的影响.研究结果表明,在经过紫外光交联后,光栅的热稳定性有较大提高,在经过高于未交联聚酰亚胺的玻璃化转变温度31℃处理2 h后,光栅形貌未发生变化.曝光前后光栅都能诱导液晶分子在表面均一沿面排列.当线性偏振紫外光的偏振方向与光栅沟槽垂直时,光交联能促进光栅对液晶的定向能力,反之则降低的定向能力.通过改变辐照光的偏振方向,调节光栅深度,能控制液晶分子在光栅上的取向方向.将这种软印刷得到的光栅用作液晶定向层,不仅可具有更好的热稳定性和定向能力,还可以调节液晶分子在光栅上的取向方向,实现多畴取向. 相似文献
9.
制备了系列含氟光敏单体材料, 六氟双酚A双肉桂酸酯(6F-BADE)与含二氟亚甲基结构的肉桂酸酯(FDE-n, n=2, 3, 4). 材料在线性偏振紫外光辐照下均可发生定向光交联反应, 通过红外光谱和凝胶渗透色谱跟踪检测, 表明光交联类型为[2+2]环加成. 单体光聚后形成的取向膜对液晶分子排列效果不同, 6F-BADE取向膜诱导液晶分子垂直排列, FDE-n取向膜诱导液晶分子平行排列. 用原子力显微镜对取向膜表面进行表征, 均未观察到明显的各向异性分布现象. 应用量子力学半经验方法AM1分析发现单体分子极性有较大差异, 认为分子极性的差异是诱导液晶取向不同的主要原因. 相似文献
10.
11.
液晶聚合物从结构上可分为3种:侧链型、主链型和主侧链型。侧链型液晶聚合物主要是聚丙烯酸酯类、聚硅氧烷类以及磷腈聚合物类。Gray等对聚丙烯酸酯类含不同取代基的联苯结构液晶聚合物进行了研究,结果表明无间隔基且取代基为氰基和饱和脂肪基时,该聚合物呈现近晶型液晶行为。为了增加介晶单元的长径比及刚性,本文在聚甲基丙烯酸酯侧链 相似文献
12.
13.
TIAN Yan-qing XU Xiao-he ZHAO Ying-ying TANG Xin-yi LI Tie-jin LI Chong-wu PAN Ang 《高等学校化学学报》1995,16(Z1):83
A new side chain liquid crystalline polymer with biphenyl mesogenic group has been prepared. This polymer forms a bilayer smectic A phase through intermolecular hydrogen bonding according to the result of X-ray diffraction. Its phase transition was studied lining DSC and polarized optical microscopy. Infrared spectroscopic measurements show that cyclic dimeric hydrogen bonds of carboxylic acids are embedded in the bilayer. 相似文献
14.
Polyaddition of 1,4-benzenedithiol (BDT) to 1,4-divinylbenzene (DVB) was carried out with 2,2′-azobisisobutyronitrile initiator in toluene at 75°C under a nitrogen atmosphere. The polymerization proceeded without an induction period, to give a white polymer with a high molecular weight (M?w = 110,000) in ca. 90% yield for 2 hr. It was confirmed by 1H-NMR (nuclear magnetic resonance), IR (infrared) and sulfur contents that the polymer had an alternating structure of DVB and BDT units. The end-capping reaction of the polymer was also achieved by addition of thiophenol and/or styrene to the polymerization solution at a final stage of the polymerization. The polymer film exhibited a reversible phase transition between a transparent state and an opaque one by thermal mode. The thermal property of the polymer was studied by differential scanning calorimetry (DSC) analysis and polarized optical microscope observation with the polymer film. The detailed DSC analysis showed that the end-capped polymer with a relatively low molecular weight (M?W = 4400–9600) exhibited similar to liquid crystalline behavior. A diffuse reflectance spectrum of the polymer coated on an aluminum plate showed a marked difference in reflective light intensity in the ultraviolet and visible regions: the reversible phase transition between an opaque and a transparent polymer layers was induced by thermal mode. The light transmittance of the polymer film, which was measured by depolarized light intensity method, was very sensitive toward the temperature variation. 相似文献
15.
J. Bonet L. Callau J. A. Reina M. Gali V. Cdiz 《Journal of polymer science. Part A, Polymer chemistry》2002,40(22):3883-3892
We modified poly(epichlorohydrin) (PECH) with biphenyl carboxylic and naphthalene carboxylic acid derivatives which contains propargyloxy moieties. The linear polymers were characterized by NMR and IR spectroscopy, elemental analysis, DSC and TGA. We obtained only one side chain liquid crystalline. A smectic A mesophase of this biphenyl derivative was identified by DSC, light polarized optical microscopy and X‐ray diffraction. Thermal crosslinking of the aryl propargyl ether group via sigmatropic rearrangement took place while the material was in the isotropic phase. Partially curing this reactive liquid crystalline polymer resulted in the formation of an anisotropic elastomer when the curing was radically initiated in the range of mesophase stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3883–3892, 2002 相似文献
16.
Garima Mishra 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):747-751
Side chain liquid crystalline (SCLC) polysiloxane polymer with a geraniol mesogenic group and polymethylene spacers were prepared, and their properties were compared with those of an equivalent SCLC polymer, SCLCP's, with phenyl benzoate mesogenic group. The phase behavior was studied by differential scanning calorimetry (DSC) and optical polarizing microscopy (OPM). The DSC curve showed a clear melting temperature and isotropization at 72 and 148°C, respectively, with a glass transition at 25°C. The observation of a fan‐shaped texture confirms the presence Smectic A phase under an optical polarized microscope. 相似文献
17.
可交联含氟聚醚醚酮的合成 总被引:2,自引:3,他引:2
聚醚醚酮 (PEEK)是一种耐热等级高、耐化学药品、耐辐射并有优异的电性能及机械性能的特种工程塑料 .由于其综合性能优异 ,PEEK在航空航天、通信、电子和机械化工等领域获得成功应用 [1] .含氟芳香聚合物以其独特的性能而成为低介电常数微电子和低损耗光波导器件极具潜力的材料 [2 ] .聚合物良好的溶解性虽对光电集成电路的加工十分重要 ,但也要满足多层化操作过程 ,还要考虑器件成型后的抗化学药品性 .因而 ,在聚合物中引入可交联组分是必要和可行的方法 .另外 ,交联后的聚合物将有更高的玻璃化转变温度 (Tg)、更好的尺寸稳定性和防开… 相似文献
18.
Guo-Ping Chang Chien Jen-Feng Kuo Chuh-Yung Chen 《Journal of polymer science. Part A, Polymer chemistry》1993,31(10):2423-2436
Alkene monomers containing phenyl or biphenyl carboxylate benzoate ester based on a mesogenic group of varied lengths of carboxyl oligo (ethanediol) monomethyl ethers as the terminal were synthesized. They were grafted onto poly(methyl-hydrosiloxane) by the platinum-catalyzed hydrosilylation process. The thermal transition temperatures and mesophase textures of monomers and of polymers were characterized by using differential scanning calorimetry (DSC), x-ray diffraction, and polarized optical microscopy with a hot stage. The factors governing mesophase textures and thermal transition temperatures are discussed. © 1993 John Wiley & Sons, Inc. 相似文献
19.
以联苯二甲酸二甲酯、二甘醇和9,10-二氢-9-氧杂-10磷酰杂菲-对苯二酚二羟乙基醚(DOPO-HQ-HE)为单体,通过无规共聚合成了一种新型含磷液晶共聚酯(PDEBP).用1H-NMR对共聚酯的结构进行了表征,用TGA、DSC和POM对其热性能及液晶行为进行了研究.结果表明,阻燃单体DOPO-HQ-HE的引入不会降低共聚酯的热稳定性,含7.5 mol% DOPO-HQ-HE的共聚酯PDEBP7.5在700℃的氮气氛中的残余物(Wt700R)可达31.9 wt%,并且具有很好的阻燃性.DOPO-HQ-HE含量的增加对共聚酯的结晶性有较大的破坏,5 mol% DOPO-HQ-HE的共聚酯PDEBP5的清亮点温度为154.2℃,焓变为4.64 J/g,而PDEBP7.5在POM测试中在升温及降温过程中均难观察到液晶相的双折射现象. 相似文献
20.
Jehan Y. Al-Humaidi Siham A. Alissa Kanubhai D. Katariya Khulood A. Abu Al-Ola Mohamed Hagar Khaled D. Khalil 《Molecules (Basel, Switzerland)》2021,26(10)
A series of high temperature alkyl and alkoxy biphenyltetracarboxydiimide liquid crystals have been prepared under ball mill method using solvent-free mechanochemical approach. The thermal properties of the prepared compounds were investigated by deferential scanning calorimetry (DSC) measurements and the textures were identified by polarized optical microscope (POM). The compounds showed smectic mesomorphic behaviour. The results showed the increasing nature of transition temperature Cr-SmC with chain length with increments of the SmC mesophase range. However, the mesophase range of the SmA was decreased with the terminal chain length either for the alkyl or alkoxy terminal groups. Moreover, the DFT theoretical calculations have been conducted give a detailed projection of the structure of the prepared compounds. A conformational investigation of the biphenyl part has been studied. A deep illustration of the experimental mesomorphic behaviour has been discussed in terms of the calculated aspect ratio. A projection of the frontier molecular orbitals as well as molecular electrostatic potential has been studied to show the effect of the polarity of the terminal chains on the level and the gap of the FMOs and the distribution of electrostatic charges on the prepared molecules. 相似文献